The present invention relates to safety ski bindings in general, and more particularly to improvements in such portions of safety ski bindings which serve to secure the skis to the heels of ski boots or other articles of footwear. Still more particularly, the invention relates to improvements in safety ski bindings of the type wherein the holding-down device for the heel of a ski boot is pivotably and shiftably mounted in a yoke which is pivoted to the ski or to a part that is mounted on the ski, wherein the holding-down device is held in the operative position by a disengageable coupling, and wherein the coupling is automatically released or disengaged in response to the application of a predetermined force to thereby allow the holding-down device to become separated from the heel.
German Offenlegungsschrift No. 1,923,882 discloses a safety ski binding wherein the holding-down device for the heel of a ski boot is biased to operative position by a compression spring which extends rearwardly of the heel and wherein the holding-down device is pivotable about an axis that is normal to the skiing direction and is located at the rear end of the spring. The pivot member for the holding-down device is mounted in elongated slots which are provided in a housing for the spring; such pivot member extends laterally beyond the housing and is rigid with a yoke which, in turn, is pivotably secured to the ski. The housing is rigid with the holding-down device and has laterally extending projections which cooperate with brackets on the yoke in such a way that, when the holding-down device engages the heel, the housing is free to move transversely of the yoke but is unable to perform pivotal movements. The projections are disengaged from the brackets only when the holding-down device is subjected to a force whose magnitude warrants a disengagement of the holding-down device from the heel. The holding-down device is then free to pivot upwardly and away from the heel. The coupling (including the projections of the spring housing and the brackets of the yoke) is disposed between the holding-down device and the pivot member at the rear end of the spring; therefore, the part including the holding-down device and the spring housing must be located at one side (below) the dead-center position whenever the holding-down device properly engages the heel. Consequently, the coupling is subjected to very pronounced stresses which oppose the movement of projections relative to the brackets, or vice versa, and the magnitude of such stresses increases if the skier decides to increase the bias of the spring. This represents an unpredicatable factor which influences the operation of the coupling and can result in injury if the coupling is not disengaged in response to the application of a certain force which acts in a direction to detach the holding-down device from the heel. Another serious drawback of the just described conventional ski binding is that the extent to which the spring housing must move relative to the yoke depends on the selected bias of the spring and hence on selected magnitude of the force which is necessary to effect a separation of the holding-down device from the heel. This is due to the fact that the pivot member for the holding-down device is located behind the spring.